In recent years, major advances in kilovolt, photoconductive semiconductor switches have been achieved, using semiinsulating high resistivity gallium arsenide as the semiconductor material As the name implies, switching is achieved when the semiconductor is illuminated, usually in the form of light energy emanating from a laser as for example, Nd:YAG laser and laser diodes. An important concern in such switches is the high voltage blocking capability. Depending on the gap length between electrodes of 0.5 to 10 mm, the semiconductor must hold off one to fifty kilovolts and conduct currents ranging from tens to thousands of amperes. The combination of electric field stress and current often results in a destructive avalanche or breakdown of the device. One of the factors contributing to the destructive avalanche is the intense electric field that exists at or very near the electrodes. Any micro- protrusion at the electrode as caused for example, by a fissure in the material, serves as a potential initiator of a filamentation channel, arising from the field re-enforcement at the site of the electrode defect. Typically, the large current densities at the microprotrusion melts the electrode material, and this produces a filamentary, conducting channel in the semiconductor. Thereafter, the switch loses its voltage hold-off capability and the semiconductor can no longer function as a switch.